A disc-type flexible couplings are known in the art. The two shafts to be connected by a disc-type coupling are each provided with a boss, also termed spider, having three extensions set at 120° one with respect to the other. The disc has six through holes or bushings for bolting equally angularly spaced from one another. The spider extensions on each shaft are bolted to the disc, but at different angular positions from those on the other shaft. A “yield” or “give” occurs, in use, when power is transmitted from one shaft to the other. This is the case in particular with rear wheel drive (RWD) vehicles, where propeller shaft or propshaft and gearbox and/or differentials are to be connected through couplings. Each bushing is connected to the adjacent ones through rubber and canvas or yarns bonded together, the yarns being wound around each couple of adjacent bushings and buried or incorporated in the rubber.
A flexible coupling constitutes a yielding intermediate element that, besides absorbing impact or shock due to irregularities in the motion of the driving shaft, allows small amounts of parallel and/or angular movement of one shaft with respect to the other. Of course, the rubber composition plays a substantial role in so far as efficiency, noise vibration and harshness (NVH) production and reliable/durable torque transmission even at relatively high temperatures, i. e. up to 120° C., are concerned.